Water-saving Irrigation Research Articles

Research and Application of Optimal Allocation Model of Water and Soil Resources from the Perspective of Ecological Economics

In order to solve the problem of realizing the rational allocation of water and soil resources in the watershed on the premise of ecological protection under the background of climate change, this paper proposes an optimal allocation model of water and soil resources from the perspective of ecological economics. In this paper, the use area of various land resources is taken as the decision variable, and the total amount of water resources available is taken as the constraint condition, and the multiobjective models under different scenarios are established, respectively. MOGWO algorithm is used to calculate the Pareto solution set under each scenario, and finally AHP is used to select the optimal solution with different decision preferences from Pareto. The experimental results show that under the current situation, the water shortage of the basin is 7.61 × 10 8 m3. In the current planning year (2020), 950.7 km2 of cultivated land should be reduced to meet the water resources situation of the river basin, accounting for about 17.8% of the total cultivated land, which is also in line with the basic policy of “well killing and land shrinking” advocated by the river basin in recent years. In the medium-term planning year (2035), the cultivated land area can be maintained at about 4300. Due to the increase of available water resources, water-saving irrigation area and irrigation water utilization coefficient, the cultivated land area in the long-term planning year (2050) can be increased by about 200 km2 on the basis of the medium-term planning year. Conclusion. The model finally obtains the optimal solution in line with different decision preferences under different scenarios.

Regional Differences and Key Influencing Factors of Fertilizer Integrated Efficiency in China

Overuse and low efficiency of chemical fertilizers have caused severe non-point source pollution in China. The investigation of regional difference and the key influencing factors of fertilization intensities (FI) and efficiency can provide references for decision-makers to establish efficient policies for fertilizer use. Using simple models of fertilizer allocation efficiency (FAE) and fertilizer integrated efficiency (FIE), it was found that the east of China excessively used fertilizers, and both the middle and west showed both excessive and insufficient fertilizer use. The average values of the FIE in the east, middle and west of China were 0.69, 0.68 and 0.64, respectively, all of which were at low efficiency. The inter-provincial differences of FIE throughout the country ranged from 0.47 in Shannxi to 0.94 in Shanghai. The population aging rate (PAR), effective irrigation rate (EIR), natural disasters affected rate (DAR) and disaster damaged rate (DDR) are considered the key factors influencing the FIE, based on the new concept of cumulative weight (CW). PAR and EIR are the positive factors, while DAR and DDR are negative. The average FIE is now 0.67 in China, which implies that the increase of chemical fertilizer use efficiency or the reduction of chemical fertilizer amount has a potential of approximate 33%, with the current grain yield and other inputs unchanged. The increase of fertilizer use efficiency should be conducted under local conditions. Optimized intensification of grain production should be given more attention in the east, and implementing disaster prevention and reduction technologies and water-saving irrigation technologies are the preference in the middle and west of China.

Non‐traditional elements of the technology of agricultural crop cultivation using fertilizers‐ameliorants

Aim. The aim of research is to determine the suitability and fertilizing value of fertilizers‐ameliorant, as well as to assess the degree of their contamination with heavy metals; approbation of fertilizers‐ameliorants in various conditions in the cultivation of agricultural crops.Material and Methodology. The main agrochemical parameters of sewage sludge and the chemical composition of glauconite were studied by analytical methods in laboratory conditions. The content of heavy metal cations in the sewage sludge was determined by atomic absorption spectrometry. The object of research in the first experiment is seed potatoes (variety Arosa); in the second experiment – safflower (variety Alexandrite).Results. Studies of the physico‐chemical parameters of the processed sewage sludge have been carried out. It has been established that the composition of the sediment is an effective organic fertilizer. The content of heavy metals in sewage sludge does not exceed the maximum allowable concentrations. It has been determined that silica is the basis of glauconite, and it also contains phosphorus, potassium and magnesium fertilizers. It has been proven that the use of sewage sludge as an independent fertilizer, as well as in combination with glauconite, has significantly increased the yield of seed potatoes and safflower.Conclusion. The use of non‐traditional ameliorant fertilizers is advisable along with the use of classical mineral fertilizers, as they allow increasing the yield of some agricultural crops, as well as achieving savings in irrigation water.

CFD simulation and experimental study of the irrigation performance of new ebb-and-flow soilless cultivation troughs

Irrigation water savings constitute an important incentive for sustainable agricultural development. Ebb-and-flow irrigation provides prominent water-saving advantages in regard to the irrigation of horticultural crops. In this study, two new ebb-and-flow soilless cultivation troughs, i.e., T- and U-type troughs, were designed based on available ebb-and-flow cultivation troughs to further improve the water use efficiency. They could be divided into substrate and water supply areas by convex separating plates. The long walls of the troughs were inclined and curved. To study the performance of these new troughs, water supply and water retention processes were analyzed using computational fluid dynamics (CFD) models. A trough with an inverted triangular profile configuration was used as the control group (CK). It was found that the water supply time consumption of the U-type troughs was the lowest, accounting for 34.48% of that of the CK troughs, and the rate of the T-type troughs was the second lowest, accounting for 55.7% of that of the CK troughs; the variation in the water retention process was negligible, at<0.5%. In addition, field experiments indicated that the U-type troughs supplied water at the highest rate and exhibited a high substrate water content, and it was determined that the U-type troughs achieved the highest irrigation efficiency, which was 1.38–1.60 times higher than that of the CK troughs, and the lowest energy consumption, accounting for 18.57%-20.28% of that of the CK troughs. Moreover, cultivation trials demonstrated that the two newly designed cultivation troughs were better than the CK trough. Consequently, the U-type cultivation trough was found to be the best choice. This study provides a theoretical basis for the ebb-and-flow soilless cultivation of horticultural crops and introduces new products to improve the irrigation water use efficiency and reduce energy consumption.

Optimizing the lateral dripline spacing of drip-irrigated aerobic rice to increase water productivity and profitability under the water-limited condition

The potential use of drip irrigation to reduce water use without yield penalty in aerobic rice cultivation has not been fully explored in the tropics due to high investment costs. One major way to lowering this cost is by optimizing the lateral spacing to serve more rows of rice plants per dripline. This study evaluates the effects of lateral dripline spacing on the grain yield, water productivity, and the economic return in aerobic rice production. Field experiments were conducted for the period of two years (2020–2021) using three lateral dripline spacings (40-cm, 60-cm, and 80-cm) as treatments and surface flooding as the control. Grain yields, water use, water productivity, and economic benefits were evaluated. The drip-irrigated aerobic rice did not show significant differences with surface flooding except for a lower yield at 80-cm in 2021 dry season due to its low percent filled grains. Among treatments, the 60-cm lateral spacing consistently obtained the highest irrigation water productivity by up to 1.03 kg m-3 and 42% irrigation water savings relative to surface flooding. Increasing the spacing of the lateral dripline decreased the material costs (80 <60 <40 cm) by 10–36%. The 60-cm spacing produced the highest average net income by 41–75% among drip treatments and had comparative economic returns compared with surface flooding. The net present value and the benefit-cost ratio indicate that it is economically viable to invest in drip irrigation using a 60-cm lateral spacing. Thus, this study suggests that when there is insufficient water to grow surface flooding aerobic rice, drip irrigation using 60-cm lateral spacing is the best option for reducing irrigation water use and increasing water productivity; while having comparative yield and economic return as surface flooding method of aerobic rice cultivation.

Study on the environmental efficiency of agricultural water resources about typical cropping patterns around the Dongting Lake area

Abstract This paper aims to evaluate the environmental efficiency of agricultural water resources utilization in different cropping patterns in the Dongting Lake area. To achieve that, the following materials are used: (1) study area: 16 counties (cities and districts) of Yueyang, Changde, and Yiyang around the Dongting Lake area; (2) data: relevant indicators of economic and environmental benefits of agricultural water resources utilization from 2011 to 2020; and (3) model: the Luenberger productivity model based on the directional distance function. With all the materials above, this paper calculates the environmental efficiency of typical cropping patterns in the Dongting Lake ecological zone and explores the spatial and temporal evolution patterns of typical cropping patterns in the lake area. The results show that (1) the environmental efficiency (LEI) of four typical cropping patterns in 16 counties (cities and districts) around Dongting Lake shows an overall increasing trend from 2011 to 2020, especially the environmental efficiency of four cropping patterns has increased significantly since 2014. (2) Among the four typical cropping patterns, the environmental efficiency of one-season rice + lobster is higher, and the environmental efficiency value of two-season rice + winter leisure is lower but most significantly improved. (3) The environmental efficiency of agricultural water resources in the hilly areas around the lake is higher than that in the Dongting Plain. Finally, some countermeasures and suggestions were put forward, such as implementing the reduction and efficiency of pesticide and chemical fertilizer in the planting industry in the lake area, optimizing the rice + planting mode, strengthening the construction of water conservation projects in the four river basins, and promoting high-standard farmland water-saving irrigation.

Durability Analysis of Small Assembled Buildings in Irrigation Canal System

With the rapid development of agricultural economy, people are paying more and more attention to how to apply high-efficiency technologies that save resources to improve agricultural production efficiency, so water-saving irrigation technology has gradually developed. China’s agricultural irrigation technology is relatively backward. In addition to the inappropriate irrigation methods and irrigation systems, problems such as siltation, seepage, and frost heave damage in irrigation canals have seriously affected the durability and service life of the canals. The backward irrigation technology seriously restricts the development of agricultural water-saving irrigation. Compared with large irrigation channels, the fabricated reinforced concrete small irrigation channels studied in this paper are less prone to frost heave damage and infiltration problems, and have the advantages of standardized production, simple transportation and installation, and convenient maintenance. In order to study the durability issues such as the basic characteristics, frost heave damage, and service life of fabricated irrigation channels, this paper takes the channel concrete and the formed channel as the research objects, and discusses the research on the properties of the channel concrete through theoretical research, numerical analysis, experiments, and other methods. Strength properties, water penetration resistance, cyanide ion penetration resistance and frost resistance; simulate the seasonal frost heave failure process of the channel; finally, on the basis of the test data, the service life aims to explore the safety and applicability of the fabricated reinforced concrete irrigation channel during the design use period.

Nitrous Oxide Emission and Grain Yield in Chinese Winter Wheat–Summer Maize Rotation: A Meta-Analysis

A systematic understanding of nitrous oxide (N2O) emission and grain yield in winter wheat–summer maize rotation, one of the most important cereal cropping systems in China, is still lacking. The primary aim of this study was to quantify the N2O emissions and grain yield, as well as responses to mitigation strategies, in this intensively managed agroecosystem. We conducted a pairwise meta-analysis by compiling a comprehensive dataset of annual N2O emissions (n = 530) and grain yields (n = 352) from peer−reviewed publications. The N2O emissions increased with nitrogen (N) fertilizer input rates following a linear model (r2 = 0.295, p &lt; 0.001), giving a specific emission coefficient and background emission of 0.71% and 0.5 kg N ha−1 yr−1, respectively. The grain yields responded to the N input rates following a linear-plateau model (r2 = 0.478, p &lt; 0.001), giving an optimal N input rate and maximum grain yield of 405 kg N ha−1 yr−1 and 15.5 t ha−1 yr−1, respectively. The meta-analyses revealed that reducing N fertilizers (approximately 50% of the full N input), water-saving irrigation, reduced or no tillage, and applying enhanced efficiency fertilizers significantly decreased N2O emissions (range: −45% to −9%) and increased or did not impact grain yields (range: −1% to 3%). We recommend that reducing agricultural inputs (i.e., N fertilizers, irrigation, and tillage) is a feasible N2O mitigation strategy in the intensively managed winter wheat–summer maize rotation that can be employed without additional environmental risks.

Riego deficitario en maíz y soja

In regions with temperate and humid climate such as Uruguay, supplementary irrigation stabilizes and increases crop yields. Irrigation on demand generates higher water consumption, which affects production system sustainability due to inefficient use of resources. In order to determine environmentally and economically more sustainable irrigation strategies, three maximum irrigation depths were evaluated in field experiment, (T2) 3 mm d-1, (T3) 6 mm d-1, (T4) 9 mm d-1 and (T1) control without irrigation, on corn and soybean production. Performance differences were observed in both crops at different water deficit levels. When precipitation (PP) was higher than average, its poor temporary distribution generated water deficit at specific times, affecting yield. T1 and T2 did not cover the crop evapotranspiration (ETc) during the critical period and grain filling, which lowered yields. T3 and T4 gave higher yields and in the three years average they were significantly different. T3 did not always cover the ETc, but the soil reserve and PP contributed to cover it, saving irrigation water. The AquaCrop model was calibrated for maize and different irrigation strategies were evaluated. The calibrated model simulated well yield, biomass and soil moisture in the irrigated treatments. In T1, the model underestimated the yield. The soil allowed for further root exploration. At 0.90 m depth, the model simulated well the yield in T1, mainly in the dry year. The model predicts the yield with a good adjustment at different irrigation and PP situations if the stress coefficients are adjusted and the crop is properly parameterized. Finally, T1, three maximum irrigation depths (3, 6 and 8 mm net) and three irrigation management (depleting 10 mm, depleting 50 % of readily available water (RAW) and depleting 100 % of RAW) were evaluated in maize with AquaCrop. The productive variables, irrigation requirement, energy demand and partial income analysis were analyzed, considering a maize crop irrigated by central pivot. It is concluded that 5 mm net gives returns and income similar to 8 mm net, without considering investment costs. Regarding management, depleting 100 % of the RAW has higher water productivity, but it is risky in dry years; however, it is feasible to vary the strategy depending on the climatic perspectives of each year.

Long-Term (1990–2013) Changes and Spatial Variations of Cropland Runoff across China

Quantitative information on regional cropland runoff is important for sustainable agricultural water quantity and quality management. This study combined the Soil Conservation Service Curve Number (SCS-CN) method and geostatistical approaches to quantify long-term (1990–2013) changes and regional spatial variations of cropland runoff in China. Estimated CN values from 17 cropland study sites across China showed reasonable agreement with default values from the National Engineering Handbook (R2 = 0.76, n = 17). Among four commonly used geostatistical interpolation methods, the inverse distance weighting (IDW) method achieved the highest accuracy (R2 = 0.67, n = 209) for prediction of cropland runoff. Using default CN values and the IDW method, estimated national annual cropland runoff volume and runoff depth in 1990–2013 were 253 ± 25 km3 yr−1 and 182 ± 15 mm yr−1, respectively. Estimated cropland runoff depth gradually increased from the drier northwest inland region to the wetter southeast coastal region (range: 2–1375 mm yr−1). Regionally, eastern, central and southern China accounted for 39% of the cultivated area and 53% of the irrigated land area and contributed to 68% of the national cropland runoff volume. In contrast, northwestern, northern, southwestern and northeastern China accounted for 61% of the cultivated area and 47% of the irrigated land area and contributed to 32% of the runoff volume. Rainfall was the main source (72%) of cropland runoff for the entire nation, while irrigation became the main source of cropland runoff in drier regions (northwestern and southwestern China). Over the 24-year study period, estimated cropland runoff depth showed no significant trends, whereas cropland runoff volume and irrigation-contributed percentages decreased by 7% and 35%, respectively, owing to implementation of water-saving irrigation technologies. To reduce excessive runoff and increase water utilization efficiencies, regionally specific water management strategies should be further promoted. As the first long-term national estimate of cropland runoff in China, this study provides a simple framework for estimating regional cropland runoff depth and volume, providing critical information for guiding developments of management practices to mitigate agricultural nonpoint source pollution, soil erosion and water scarcity.

Securing Flows in the River Systems through Irrigation Water Use Efficiency—A Case Study from Karula River in the Ganga River System

The pressure on freshwater resources is leading to diminishing flows in some of the critical river systems across the globe. India is no exception, and this is mainly because of water withdrawal for irrigation, which is often to the tune of 70% to 80% of the lean season flows, with some proportion for domestic and industrial use. While graduating from the concept of environmental flows and its assessment methodologies in India, the water-managers, the researchers and the conservationists are now moving towards answering the next question, if the rivers are to be revived, where will the water come from, especially in the case of over-allocated rivers, including the River Ganga. While the logical way is to look at the biggest user of water, i.e., irrigation, it remains to be seen whether the irrigation water savings will actually lead to enhancing flows in a river, complementing the efforts towards maintaining e-flows in rivers, or whether it will lead to more area under agriculture, bring changes in cropping patterns towards more water-intensive crops or result in something else. This is a growing debate across the globe, where India is no exception, and there has been a wide range of opinions in this regard. This paper discusses the process, findings and lessons from a joint initiative involving farmers, the Uttar Pradesh state Irrigation and Water Resources Department, Bijnor District Administration and a conservation organisation, WWF, to enhance flows in a sub-tributary, called the Karula River, which is part of the Ganga River system. Another objective of this paper is to look at the scalability and replicability of similar approaches in other irrigation command areas to benefit nearby river systems in general. Under this initiative, the team attempted to enhance flows in the river Karula by routing the saved water from irrigation supplies in a canal commanded area. This saving of water is being achieved due to supply-side and demand-side measures that are being adopted in the project area. With the objective of ensuring the sustainability of the initiative, efforts are made to form an institutional arrangement, through which this initiative can be sustained beyond the project support.

Regional modeling of winter wheat yield and water productivity under water-saving irrigation scenarios

Abstract Wheat is the major agricultural crop in Iran. Using reliable tools to estimate wheat grain yield may help the regional planners and stakeholders to employ proper cultivation approaches to increase grain yield in different regions. The process-based crop growth models are the essential analytical tools for representing the main interactions between the environment, crop, resources, and yield production. For these reasons, the crop growth models have been used as an important component in productive farming systems for assessing and improving the crop production at field and regional scales. In this study, the parameterized AquaCrop model was employed to simulate the four major elements that affect the crop growth process, such as soil water content, canopy cover, biomass, and grain yield, of three irrigated winter wheat cultivars. The field experiments were conducted in four locations with different climatic conditions in the south and southwest of Iran during three consecutive growing seasons of 2016–2017, 2017–2018, and 2018–2019. Results showed that AquaCrop had reliable simulation of soil water content with normalized root mean squared error (NRMSE) and Nash–Sutcliffe coefficient (CNS) ranging from 0.05 to 0.15 and 0.69 to 0.85, respectively, for the four study locations. The NRMSE and CNS ranged from 0.10 to 0.21 and 0.83 to 0.97 for canopy cover, respectively. The NRMSE and CNS values were 0.11–0.26 and 0.80–0.97 for biomass, respectively. These results indicate that the parameterized AquaCrop model has high skill in the simulation of soil water content, canopy cover, biomass, and grain yield of different winter wheat cultivars in the vast regions in the southern part of Iran. The model was then used to simulate wheat grain yield and irrigation water productivity (WP) for 324 scenarios, including nine sowing dates, three irrigation levels, and three climatic conditions. AquaCrop showed that it was skillful to simulate grain yield and WP of different irrigated winter wheat cultivars in different regional climatic conditions, deficit irrigation levels, and sowing dates. Overall, the AquaCrop model could be used as a reliable decision-making tool for the field managers and stakeholders.

Winter drainage and film mulching cultivation mitigated CH4 emission by regulating the function and structure of methanogenic archaeal and fermenting bacterial communities in paddy soil

AbstractWinter flooding of harvested rice fields is a typical cropping system in mountainous areas, which emits considerable amounts of CH4. Plastic film mulching cultivation is recognized as an important rice cultivation practice in paddy field for water-saving irrigation. However, the effects of these managements on CH4 emissions in paddy soil and the underlying microbial mechanism are unclear. A field experiment was carried out with the application of winter drainage followed by traditional rice cultivation (WD), winter drainage followed by plastic film mulching cultivation (MC), as well as winter flooding followed by traditional rice cultivation (WF) as control in hilly paddy fields. We investigated the CH4 emissions, functional (CH4 production rate, 13C isotope) and structural (abundance, structure) responses of soil methanogenic archaeal and fermenting bacterial communities during rice season. Shifting the fields from WF into WD and MC substantially mitigated CH4 emissions by 62.3% and 59.2%, respectively, paralleled with the enhancement of soil Eh and the reductions of soil DOC content. Compared with WF, WD and MC both significantly decreased CH4 production rates and the copy numbers of mcrA gene. Moreover, an increasing contribution of hydrogenotrophic methanogenesis (from 30.7% to 50.0%) to total CH4 production was observed during the conversion from WF to MC under an anaerobic incubation, paralleled with the decreased acetate content and increased δ13C values of acetate-methyl and total acetate. The communities of methanogenic archaea and fermenting bacteria strongly responded to the shift from WF to WD, while MC only showed significant effects on the methanogenic archaeal communities. Compared with WF, WD and MC significantly increased the relative abundance of Methanothrix, Methanosarcina and Methanocella, while those of Methanoregula, Massilia and Geobacter were decreased. The co-occurrence networks showed that WD and MC induced the loss of mixed methanogenic fermentation modules, indicating the decrease in functional biodiversity and redundancy of fermenting bacterial and methanogenic archaeal communities.The findings suggest that WD and MC approach mitigate CH4 emission by regulating the function and structure of methanogenic archaeal and fermenting bacterial communities in paddy soil, which represent the effective management strategies considering the water availability and CH4 mitigation in paddy-field agriculture.

Modelling water and energy fluxes with an explicit representation of irrigation under mulch in a maize field

Globally, water-saving irrigation plays a vital role in agricultural ecosystems to achieve sustainable food production under climate change. Irrigation under mulch (IUM) system has been widely used in modern agricultural ecosystems due to its high water use efficiency, but it remains unclear how each component of the water and energy processes responds to this agricultural management practice. Current modeling approaches are inadequate in investigating the impacts of IUM management on water-energy balance, which have shown more complicated than non-mulched management. Therefore, this study provided an explicit simulation of water and energy fluxes in IUM system using a process-oriented ecosystem model—CoupModel and the three years of the eddy covariance (EC) measurements. Based on Monte Carlo and the multiple model performance evaluation criteria, most of the model sensitive parameters were well constrained and 32 potentially important parameters, e.g., iscovevap, the fraction of mulch coverage, were identified to characterize the impacts of plastic mulching on energy balance and water transport. After proper calibration, the coefficient of determination (R2) for measured and simulated soil temperature (T) and soil water content (SWC) was 0.79 and 0.60, respectively, and the R2 for T and SWC during the validation period were 0.91 and 0.71, respectively. Furthermore, we found that there was a strong coupling between the parameters of the water and energy processes, which would restrict the simulation results due to the correlation between the parameters and the evaluation indices. This study presented a systematic model parameters calibration in the agricultural ecosystem implemented with IUM and provided with a more comprehensive understanding of the water and energy balance in cropland. These results would help agricultural model development with more detailed considerations of the water-saving management.

Optimization of Planting Structure under the Background of Water-Saving Irrigation in Shiyang River Basin, China

Optimization of Planting Structure under the Background of Water-Saving Irrigation in Shiyang River Basin, China

Impact of Different Colour Low Tunnel Shade Nets and Mulches on Water use Efficiency and Nutrient use Efficiency in Chrysanthemum

An investigation was carried out in an experimental field of the College of Agricultural Engineering, University of Agricultural Sciences, Raichur, to investigate the effect of different coloured low tunnel shade nets and different mulches on water use efficiency and nutrient use efficiency of chrysanthemum. The results revealed that the values of daily evapotranspiration under different colours’ low tunnel shade net were less than the values of evapotranspiration under open field for all months. It is because of the green-house effect and low radiation. The values of ET during the seasons were lower under white-coloured shade net compared to open field conditions. The results indicate that significant irrigation water savings occur in chrysanthemums under different coloured low tunnel shade nets as compared to open field cultivation. It is also found that the chrysanthemum crop requires approximately 31%, 28%, and 23% less water under white, green, and black shade net compared to the total water required under open field cultivation. The highest water use efficiency was recorded with the white colour low tunnel shade net (28.78 kg ha-1 mm-1) and this was followed by the green shade net (28.64 kg ha-1 mm-1), black shade net (13.09 kg ha-1 mm-1) and lowest water use efficiency was recorded under open field conditions (10.58 kg ha-1 mm-1). Among the different mulches, the highest water use efficiency was recorded by the use of white coloured mulch (24.36 kg ha-1 mm-1) and this was followed by silver mulch (21.75 kg ha-1 mm-1), black mulch (20.82 kg ha-1 mm-1), and jute mulch (19.38 kg ha-1 mm-1). The lowest water use efficiency was recorded where mulch was not used (15.05 kg ha-1 mm-1). The highest nutrient use efficiency was recorded with the white colour low tunnel shade net (Nitrogen (N)=72.51 kg ha-1, Phosphorous (P)=12.37 kg ha-1 and Potassium (K)=73.84 kg ha-1 ) and this was followed by the green shade net (N=66.77 kg ha-1, P=10.28 kg ha-1 and K=64.33 kg ha-1), open field conditions (N=58.08 kg ha-1, P=8.72 kg ha-1 and K=56.36 kg ha-1) and lowest nutrient use efficiency was recorded under black shade net (N=51.60 kg ha-1, P=6.98 kg ha-1 and K=49.75 kg ha-1). Among the different mulches, the highest nutrient use efficiency was recorded by the use of white colour mulch (N=77.53 kg ha-1 P=11.74 kg ha-1 and K=73.20 kg ha-1) and this was followed by silver mulch (N=70.50 kg ha-1, P=10.61 kg ha-1 and K=66.86 kg ha-1), black mulch (N=65.08 kg ha-1, P=9.51 kg ha-1 and K=64.09 kg ha-1), and jute mulch (N=57.75 kg ha-1, P=8.96 kg ha-1and K=64.09 kg ha-1). The lowest nutrient use efficiency was recorded where mulch was not used (N=40.22 kg ha-1, P=7.11 kg ha-1 and K=44.44 kg ha-1). The results indicated that there is a bright scope for cultivation of chrysanthemum under white colour low tunnel shade net with white plastic mulch.

Evaluation of Cultivated Land Quality in Semiarid Sandy Areas: A Case Study of the Horqin Zuoyihou Banner

Objective: The evaluation of cultivated land quality from the regional perspective and the clear level and change in cultivated land quality in the whole region can better guide the construction of cultivated land quality, carry out scientific optimization allocation, improve grain production capacity, and promote the sustainable use of cultivated land. Research methods: The utilization of local resources and natural conditions were comprehensively considered, and the evaluation was carried out from the four dimensions of ecology, quantity, spatial structure and scale to comprehensively reflect the level of regional cultivated land utilization. Results: (1) The cultivated land quality level of the Horqin Zuoyihou Banner is low, and the pressure of regional water resources is great. Some cultivated land is located in the area with poor natural conditions, and there are many thin and narrow cultivated areas of land. The area of cultivated land that can be carried by regional water resources under current irrigation is 184,492.17 hm2, and that under water-saving irrigation is 259,703.72 hm2, which are lower than the current cultivated land areas. (2) During the study period, the total amount and spatial distribution of cultivated land changed greatly, and there were good natural conditions and utilization conditions of newly added cultivated land, but the quality of cultivated land from the regional perspective showed a downward trend. The dynamic attitude of cultivated land change was 0.99%. (3) According to the evaluation results, the cultivated land was divided into the following four categories: priority protection type, optimization and coordination type, gradual conversion type and priority conversion type, which accounted for 34.18%, 30.59%, 28.83% and 6.40% of the total cultivated land area, respectively. Conclusions: There is a sharp contradiction between the supply and demand of water resources, and the quality of cultivated land in the region is low and shows a downward trend, which is not conducive to the sustainable use of regional land resources. In this regard, the Horqin Zuoyihou Banner should actively curb the growth of cultivated land, develop water-saving irrigation processes, strengthen ecological environment protection, and systematically optimize the layout of cultivated land on the premise of ensuring ecological security according to the actual conditions of different regions.

Effects of Humic Acid Organic Fertilizer on Soil Environment in Black Soil for Paddy Field Under Water Saving Irrigation

In the past decades, the application of organ fertilizer in agricultural soils has attracted wide attention. However, few studies have carefully explored the effects of humic acid organic fertilizer on soil microbial colonies, soil enzyme activities, and soil fertility. To provide a better growing environment for crops, we explore the best regulation mode of humic acid organic fertilizer in the farmland in the Songnen Plain Heilongjiang province. Through field experiment, we selected paddy as the test objective and applied humic acid organic fertilizer. Under the condition of water-saving irrigation, five fertilization levels were set up, which were NPK (local nitrogen level, 110 kg.hm-2 pure nitrogen), NPKH1 (450 kg.hm-2 humic acid organic fertilizer + 77 kg.hm-2 nitrogen), NPKH2 (750 kg.hm-2 humic acid organic fertilizer + 55 kg.hm-2 nitrogen), NPKH3 (1050 kg.hm-2 humic acid organic fertilizer + 33 kg.hm-2 nitrogen) and PKH (1500 kg.hm-2 humic acid organic fertilizer). The effects of different humic acid organic fertilizers on soil microbial colonies, soil enzyme activities, and soil fertility were discussed. The results showed that humic acid organic fertilizer could effectively change the structure of soil microbial colonies, soil enzyme activities, and soil fertility. Compared with NPK treatment, the bacteria, fungi, and actinomycete, urease, and catalase in PKH, NPKH3, NPKH2, and NPKH1 treatments increased, and significantly different under 0-10 cm layer conditions (P&lt;0.05). With the increase of humic acid organic fertilizer application, soil organic matter and soil fertility from superior to inferior was PKH&gt;NPKH3&gt;NPKH2&gt;NPKH1&gt;NPK. Therefore, the application of humic acid organic fertilizer was an effective measure to improve soil fertility and increase the amount of soil colony structure and enzyme activities.

Critical Role of Irrigation Efficiency for Cropland Expansion in Western China Arid Agroecosystems

AbstractThe rapid expansion of desert croplands in the Tarim River Basin, which depend heavily on irrigation with meltwater, has coincided with increases in snow and glacier melt in the high mountains of Asia during the past decades. Meanwhile, there have been intensive investments in modern irrigation technology aimed at enhancing water use efficiency. The importance of meltwater in mountain front agroecosystems has been widely acknowledged, but it is not clear how important this meltwater versus increased irrigation efficiency (IRE) has been for the rapid cropland expansion in the Tarim River Basin. Here we investigate changes in water supply and demand of the meltwater‐irrigated cropland bordering the Taklamakan Desert based on multiple remotely sensed and ground‐based observation datasets, and we evaluate the contributions of improved IRE to cropland expansion. We find that cropland has increased by 58% between 1990 and 2015. Net streamflow to the region increased by +10% over the same period, but the rate of increase was slower after 2000. This deceleration contrasts with the growing irrigation demand (IRD) imposed by dramatic cropland expansion. At the same time, IRE increased by 73% from 1990 to 2015, providing 18.5 billion m3irrigation water savings, which offset the increased IRD. With the adoption of more efficient irrigation, crop water stress due to continuous agricultural expansion in the Tarim River Basin declined significantly, making the dependence of agricultural production on runoff from glacier and snow meltwater less than would otherwise be expected.

Wheat yield modeling under water-saving irrigation and climatic scenarios in transition from surface to sprinkler irrigation systems

• Remote sensing can provide historical growth data for crop modeling on large scales. • Water productivity could be improved by 18% by deficit irrigation. • Irrigation could be reduced by 150 mm in wet and normal years with no yield loss. • Irrigation strategy under erratic rainfall is vital in improving water productivity. • Sprinkler irrigation in dry years decreased water productivity. Water-saving through deficit irrigation management is a prominent approach to improving water productivity (WP) in sustainable agriculture. However, it is not feasible to assess many irrigation scenarios and their impact on WP. Therefore, crop modeling is a valuable tool for evaluating the effect of different irrigation scenarios on yield and WP. No study has evaluated surface irrigation and transition to sprinkler irrigation under different climatic scenarios and irrigation strategies. In this study, historical remotely sensed crop growth and field-measured grain yield (GY) data were used to calibrate and validate the AquaCrop model for a wide wheat-cultivated area. Then, the model was used to investigate the impact of different surface deficit irrigation strategies under five different climatic scenarios, including wet, normal, and dry on WP and GY. Then the model was used to assess the effect of different sprinkler irrigation strategies and their application efficiency on WP and GY under the climatic scenarios. Based on AquaCrop scenario analyses, irrigation water requirements varied between 270 and 620 mm in different growing seasons regarding rainfall characteristics (amount and distribution). Also, reducing irrigation water by 30% improved WP between 0% and 18% in different growing seasons. Moreover, sprinkler irrigation could improve WP and sustain yield production only in normal and wet years with high application efficiency and proper irrigation strategy. Otherwise, sprinkler irrigation would decrease WP and increase the pressure on water recourses. Therefore, in such areas with erratic rainfalls, synchronizing irrigation strategy with the rainfall characteristics increases WP and sustains crop production.